Multimedia Systems Lecture - 2
Lecture Outline • Multimedia Formats • Sound/Audio formats • Video formats • Image formats
Multimedia Formats • The specific arrangement of multimedia (data) in a file or storage device is known as its format. • The format can be observed from the final letters of the file’s name (following the dot), such as the WMV in myclip.wmv.
Sound/Audio Formats • MIDI • Real Audio • AU • AIFF • SND • WAVE • MP3 (MPEG)
MIDI Format • MIDI - Music Instrument Digital Interface • It was developed in 1982 by the music industry. • It is used for sending music information between electronic music devices such as like synthesizers and PC sound cards. • MIDI allows computers, synthesizers, MIDI controllers, sound cards, samplers and drum machines to control one another and exchange system data.
MIDI Format (Contd.) • MIDI files do not contain sampled sound/audio signal, but a set of digital musical instructions (musical notes) that can be interpreted by the PC's sound card. MIDI transmits • "event messages" such as the pitch and intensity of musical notes to play, • control signals for parameters such as volume, vibrato, cues, etc. and • clock signals to set the tempo • Downside - it cannot record sounds (only notes). In other words - It cannot store songs, only tunes.
MIDI Format (Contd.) • Upside - since it contains only instructions (notes), MIDI files can be extremely small. For example, a 23K file can play for 5 minutes. • This format is supported by many different software systems over a large range of platforms. MIDI files are supported by all the popular Internet browsers. • Sounds stored in the MIDI format have the extension .mid or .midi.
Real Audio Format • The RealAudio is a proprietary audio format developed for the Internet by RealMedia (a.k.a. RealWorks). • The first version of RealAudio was released in 1995. The current version is RealAudio 10 (as of 2008) • The format allows streaming of audio (on-line music, Internet radio) with low bandwidths. But low bandwidth priority often reduces quality. • It uses a variety of audio codecs, ranging from low-bit rate formats (for dialup modems) to high fidelity formats. Audio Streaming = audio is played at the same time as it is downloaded
Real Audio Format (Contd.) • In 1997, RealNetworks offered a video format “RealVideo”. • The combination of audio and video formats was termed as RealMedia (file extension .rm). • The official player for RealMedia content is RealPlayer. • Sounds stored in the RealAudio format have the extension .rm or .ram (real audio metadata). • More recently, audio-only files use extension .ra and video files (with or without audio) use extension .rv
AU Format • The AU format is simple audio format introduced by Sun Microsystems. • It is supported by many different software systems over a large range of platforms. • Sounds stored in the AU format have the extension .au
AIFF Format • AIFF - Audio Interchange File Format • The AIFF format was developed by Apple. • AIFF files are not cross-platform and the format is not supported by all web browsers. • Sounds stored in the AIFF format have the extension .aif or .aiff
SND Format • The SND (Sound) was developed by Apple. • SND files are not cross-platform and the format is not supported by all web browsers. • Sounds stored in the SND format have the extension .snd
WAVE Format • The WAVE (waveform) format is developed by IBM and Microsoft. • It is supported by all computers running Windows, and by all the most popular web browsers. • Sounds stored in the WAVE format have the extension .wav
MP3 (MPEG) Format • MP3 files are actually MPEG files. MPEG format was originally developed for video by the Moving Pictures Experts Group. We can say that MP3 files are the sound part of the MPEG video format. • MP3 is one of the most popular sound formats for music recording. • The MP3 encoding system combines good compression (small files) with high quality. Expect all your future software systems to support it. • Sounds stored in the MP3 format have the extension .mp3, or .mpga (for MPG Audio)
Which Sound Format To Use? • The WAVE format is one of the most popular sound format on the Internet, and it is supported by all popular browsers. • If you want recorded sound (music or speech) to be available to all your website visitors, you should use the WAVE format. • The MP3 format is the newer format for recorded music. • If your website is about recorded music, the MP3 format is the choice of the future.
Video Formats • AVI • Windows Media • MPEG • Quick Time • Real Video • Shock Wave (Flash) • Windows (specific) Multimedia Formats
AVI Format • AVI- Audio Video Interleave • It was developed by Microsoft to store audio and video data for simultaneous playback. • It is supported by all computers running Windows, and by all popular web browsers. • It is a very common format on the Internet, but not always possible to play on non-Windows computers. • Videos stored in the AVI format have the extension .avi.
Windows Media format • The Windows Media format was developed by Microsoft. • It is part of Windows Media Framework. • It is a common format on the Internet, but Windows Media movies cannot be played on non-Windows computer without an extra (free) component installed. Some later Windows Media movies cannot play at all on non-Windows computers because no player is available. • Videos stored in the Windows Media format have the extension .wmv.
MPEG Format • MPEG - Moving Pictures Expert Group • This format is the most popular format on the Internet. It is cross-platform, and supported by all the most popular web browsers. • MPEG-4 is a very good quality standard with low file sizes. • Videos stored in the MPEG format have the extension .mpg or .mpeg
MPEG Format (Contd.) • Developed in the late 1990s, MPEG-4 development was initially supported by many companies including Apple and Microsoft, but Microsoft has since abandoned active support. Apple Quicktime continues to support MPEG-4, as do other companies such as DivXNetworks. • The MPEG-4 has variations, some are ISO-compliant and some aren't. Some MPEG-4 files play in any player, others will only work in certain players. • Numerous applications are available to create MPEG-4, the best-known being Apple QuickTime Pro.
QuickTime Format • The QuickTime format is developed by Apple. • It is a common format on the Internet, but QuickTime movies cannot be played on a Windows computer without an extra (free) component installed. • Using advanced features of QuickTime, a user can create interactive video, panoramas, virtual reality settings and more. • Videos stored in the QuickTime format have the extension .mov.
QuickTime Format (Contd.) • QuickTime format has been around since the beginning of digital video production. • In many ways QuickTime is more complicated than Windows Media or Real Media. • Some users comment that getting good quality video can be a challenge and that default settings are rarely good enough and experimentation is essential. • QuickTime can be integration with other products. It is widely supported by many editing, authoring and general interest applications.
Real Video Format • The RealVideo format was developed for the Internet by Real Media. • The format allows streaming of video (on-line video, Internet TV) with low bandwidths. Because of the low bandwidth priority, quality is often reduced. • Videos stored in the RealVideo format have the extension .rm or .ram
Real Video Format (Contd.) • Real Media was one of the first serious streaming video solutions. • In the early days it was widely considered to be the best streaming format. It is still a good format but it has lost a lot of ground in the format wars. • Real Media video images tend to be slightly less sharp than other formats — this can be a good or bad thing depending on your preferences. • Moving images are handled reasonably well but the finer detail can be easily lost. Overall image quality is perfectly adequate for most applications. • One big disadvantage is the difficulty in downloading the free Real Media Player. Real Media has struggled to maintain a viable commercial business model and they strongly encourage you to buy the full version. This has led many people to become disillusioned with the format and its reputation has not held up well over recent years.
Shockwave (flash) Format • The Shockwave format was developed by Macromedia. • The Shockwave format requires an extra component to play. This component comes preinstalled with the latest versions of Netscape and Internet Explorer. • Videos stored in the Shockwave format have the extension .swf. • Flash uses two main formats • .swf - for standard Flash files used in web pages • .flv - a special Flash video format. flv files can be called from within swf files. • As of late 2008 Flash also supports H.264 files
Shockwave (flash) Format • Flash is very powerful and flexible - it enables the user to create custom controls and menus, interactive video and animations, advanced integration with web pages, etc. • Flash also has the huge advantage of having the most widely-supported cross-platform player.
Windows Multimedia formats • Windows media files have the extensions .asf, .asx, .wma, and .wmv • .ASF • Advance Streaming Format - developed by Microsoft in 1995 to store streaming media online (on-line TV or radio). • ASF files can be highly compressed. Files can be compressed to match many different bandwidths (connection speeds). • ASF files can be viewed while being downloaded. • PowerDVD, WinDVD, CinePlayer Surround, Easy DVD Player, Super DVD Player, Magic DVD, and Zoom player play this format.
Windows Multimedia formats • .ASX • Advanced Stream Redirector files are not media files, but metafiles. • Metafiles provides information about files. • ASX files are plain text files used to describe multimedia content. • When the ASX file is read by a player, the player can play the files described.
Windows Multimedia formats • .WMA • Windows Media Audio - an audio format developed by Microsoft. • WMA is designed to handle all types of audio content. The files can be highly compressed and delivered as a continuous flow of data (on-line radio). • WMA files can be of any size, and be compressed to match many different bandwidths (connection speeds). • The WMA format is similar to the ASF format.
Windows Multimedia formats • .WMV • Windows Media Video – a video format developed by Microsoft. • Designed to handle all types of video content. The files can be highly compressed and delivered as a continuous flow of data. • Similar to ASF format. • Other windows media formats • WAX (Windows Media Audio Redirector) files are much the same as ASX files, but intended to describe audio files (.wma files) • WMP (Windows Media Player) files and WMX are reserved file types for future use by Windows
Image Formats • GIF • PNG • JPEG • TIFF • EXIF • WMF • BMP • PAINT & PICT (Mac based)
GIF • Graphics Interchange Format – a bitmap image format • Introduced by CompuServe in 1987 to distribute images across network and widely used on WWW since then. • It is the first graphic file type recognized by early web browsers. • It supports animation. • Available in two versions • GIF87a (original) • GIF89a (enhanced)
GIF features • GIF87a • Limited color palette • A GIF image can contain 2, 4, 8, 16, 32, 64, 128 or 256 colors • Interlacing • It is a mechanism that makes images appear faster on-screen • First pass has pixel rows 1, 9, 17, etc (every eighth row) • Second pass has rows 5, 13, 21, etc. (every remaining fourth row) • Third pass has rows 3, 7, 11, 15, etc. (every remaining odd row) • Fourth pass has rows 2, 4, 6, etc. (all the even-numbered rows)
GIF Features • LZW Compression • GIF images are compressed using LZW compression (loss less). • Animation • Allows timed display of images in sequence, giving the effect of animation • GIF89a • All the features in GIF87a • Delay times, image replacement parameters • Back ground transparency
GIF (Contd.) • When to use GIF? • Images with areas of flat color, such as logos, line art, icons & cartoon-like illustrations • Not much suited for photographic images • Suited for adding simple animation • Whenever transparency in image is required (even though PNG supports this feature, not all web browsers supports it)
PNG • Portable Network Graphics • Developed in early 1995 as nonproprietary alternative to GIF • Three advantages over GIF • Alpha channels* • Gamma correction* • 2D Interlacing* • Supports 48 bit color • Supports lossless compression • Does not support multiple image format/ animation like GIF
JPEG • Joint Photographic Experts Group - widely used image format for photographic images. • Created by the working group JPEG of ISO/IEC. • Lossy compression used in JPEG . • Tradeoff between image quality and storage size -For a Quality factor 75%, JPEG achieves image size around 6% of original size. • File extensions for files using JPEG compression are .jpg and .jpeg, .jpe, .jif and .jfif are also used. JPEG 2000 and JPEG XR*
Other Formats • TIFF (Tagged Image File Format) • EXIF (Exchange Image File) • WMF (Windows Meta File) • BMP (BitMaP) • PAINT & PICT (MacPaint & MacDraw programs in Mac system)
TIFF • Tagged Image File Format - a file format created by Aldus, for storing images, including photographs and line art. • In beginning, TIFF was a binary format (since desktop scanner could handle black & white). As scanners and computers (that store scanned images) became more powerful, TIFF format also improved to support grayscale and then color images. • TIFF format is widely supported by • image-manipulation applications, • publishing and page layout applications, • scanning, faxing, word processing, optical character recognition and other applications
EXIF • Exchangeable Image File Format – image file format used by digital cameras. • It uses existing JPEG, TIFF Rev. 6.0 and RIFF WAV file formats with the addition of specific metadata tags. • It was created by Japan Electronic Industries Development Association (JIEDA)
WMF • Windows Metafile – a graphic file format on Microsoft systems. • WMF files may contain both vector and bitmap components. • Most Windows clipart is in WMP format. • With vector graphics, WMF store images in very less space. • WMF is a 16-bit format introduced in Windows 3.0. A newer 32-bit version with enhancements is called EMF (Enhanced Metafile).
BMP • Bitmap file format – used to store bitmap digital images especially on Windows and OS/2. • Most BMP files have large size due to lack of compression but many can be compressed with lossless data compression algorithms such as ZIP.
Assignment • Short Presentation on terms marked with * and • MPEG-1, MPEG-2, Other MPEG standards (2 to 3) • JPEG 2000 and JPEG XR • Vector Graphics, Raster Graphics • GDI